Why my site is running slowly?

I think my site (www.luchotv.com) is running slowly.
Is there any way to know what factor ( or factors ) are making it slow?
Could it be the hosting provider?
Another option could be my internet service being too slow.
Too many variables, is there any way to accurately determine the performance issues of my site?
By the way, I installed w3 total cache and the speed improved, but I would like to know how to improve it without the plugin :slight_smile:
Thank you,